tippy2k2 said:
To my knowledge from my film minor days, there is one easy way to tell the difference between a MacGuffin and what's not a MacGuffin:
If the object that you are chasing could be changed to anything else and it would not change the movie in any way, then you are chasing a MacGuffin.
The orb is not a MacGuffin because it becomes pretty damn important in the plot.
I always hated that particular definition because "being interchangeable" is such a nebulous concept.
If a thief is trying to steal something valuable that valuable thing could be anything without changing the story, but if that same thief was trying to steal a key to a safe with a valuable thing in it, the key has to be a key but that doesn't suddenly make it not a MacGuffin.
Or a story where the hero has to rescue the princess from the tower.
The princess is a MacGuffin but is she interchangeable?
A MacGuffin is just a thing that's only there to drive the plot, regardless of how unique it is.
I've also never heard a definition of MacGuffin that extends to whether it was used in the narrative.
The only definition I know says it's a MacGuffin if it's introduction is not a direct result of an event in the plot, (Usually at the beginning of a story)